Electric power conversion device 9 of the current inject type shown in FIG. 19 (DC/DC converter) is known so far.
This electric power conversion device 9 consists of the control circuit 91, the driving circuit 92 and the converter circuit 93. The converter circuit 93 consists of the power supply Ei, the transistor switch Tr, the resistance Rs for detecting current, the inductor L, the flywheel diode FD, and the output capacitor C.
The control circuit 91 detects the current that flows in output voltage eo and the inductor L as voltage down es of the resistance Rs.
The control circuit 91 controls input current ii by operating the transistor switch Tr on-off so that eo may approach eo* (deflection must become 0), referring to the value of voltage down es.
In this electric power conversion device 9, the value in which preset gain Kp is multiplied to deflection named eo and e0* as shown in FIG. 19 and the value in which compensatory signal Sh was added to bias ec are added. And peak voltage ep are made.
The comparator compares peak voltage ep and voltage Vs (it is generated with putting preset gain Acc on voltage descent es). And, the comparison result is input to the flip-flop FF circuit that operates by driving signal SS (sampling cycle Ts). As a result, control signal Sc of which the duty is the time to reaching to the peak voltage ep is generated. The driving circuit 92 controls transistor switch Tr based on this control signal Sc.
By the way, the response accuracy of electric power conversion circuit 9 of FIG. 19 (control accuracy) depends on the resolution of control signal Sc as shown in FIG. 20. The frequency of the practicable oscillator used for the electric power conversion circuit 9 is 100 MHz now. Therefore, the response accuracy of electric power conversion circuit 9 is not good.
The purpose of the present invention is to be able to on-off control the current that flows from the power supply aiming at the inductor in high accuracy and to digitalize the control operation circuit.